Hearing through the Noise (when older): Irrelevant Stimuli and Word Recognition among the Old

 “Forever young, I want to be forever young. Do you really want to live forever, forever forever

Do you share the same sentiment/s with this famous song by Alphaville? I too, at an early age of 20, want to be forever young. Why? Because being young involves lesser responsibilities and workload as compared to that of an adult. And biologically speaking, being younger means being more physically fit and having more accurate perceptual processes. For instance, babies have a relatively sharper sensory system as compared to adults (Santrock, 2011). However, getting old is inevitable. It is for this reason that as we grow older, we should learn how to adapt to how our body functions at every age.

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A forever young Peter Pan

A common difficulty in the functioning of older people is in their sense of hearing. According to the Committee on Hearing, Bioacoustics and Biomechanics (1988; as cited in Li, Daneman, Qi & Schneider, 2004), older adults often report that they have difficulty understanding speech in everyday conversational settings, especially when the environment is noisy and when there is more than one person speaking at a time. This is difficult because everyday life is composed, more or less, of situations that are heavily bombarded with conversation and speech. Older people frequently find themselves in instances like this (e.g., family gatherings, mall conversations). Thus, they are prone to frustration and anxiety, and they may avoid or be excluded altogether from social interactions. Moreover, studies has shown that older adults with normal or near-normal hearing may have no difficulty  perceiving speech in quiet listening conditions, but they do have considerable difficulty when there are interfering stimuli or when they are tested in reverberant environments (Stuart & Phillips, 1996; Tun & Wingfield, 1999; Schneider, Daneman, & Pichora-Fuller, 2002; Li et al, 2004).

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Age-related difficulties in understanding speech could arise from several different sources: 1. deterioration of auditory resources 2. slowing of brain functioning and cognitive processing and 3. difficulty in inhibiting the processing of irrelevant stimuli. In this post, I will focus on the last source which is filtering out of irrelevant stimuli.

It has been proposed that normal aging is associated with reduced inhibitory mechanisms for suppressing the activation of goal-irrelevant information (Hasher & Zacks, 1988; Hasher, Zacks, & May, 1999; Li et al, 2004), allowing interfering signals to intrude into working memory. Thus, older adults may find hearing in noisy backgrounds to be difficult not only because of auditory declines but also because they cannot inhibit the processing of irrelevant speech efficiently.

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In the study conducted by Li, Daneman, Qi & Schneider (2004), they tested the hypothesis that older adults should have more difficulty inhibiting the irrelevant masker, particularly when the masker and target are both speech. They did this by comparing the performance of older adults with younger adults. To determine whether older adults find it difficult to inhibit the processing of irrelevant speech, they asked both the younger and older adults to listen to and repeat meaningless sentences (e.g., “A rose could paint a fish”) when the perceived location of the masker (speech or noise) but not the target was manipulated. Separating the perceived location (but not the physical location) of the masker from the target speech produced a much larger improvement in performance when the masker was informational (2 people talking) than when the masker was noise.  However, contrary to the expected result, the size of this effect was the same for younger and older adults, suggesting that the interference from an irrelevant source at the cognitive-level was no worse for older adults than it was for younger adults.

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            So now, based from the results, we can conclude that the difficulties in sound localization among older adults are not caused by any age-related factor. However, it is helpful to note that the study used a simple word recognition task. The results may be different had they used a more meaningful sentence. In conclusion, what we can learn from this study is that we should be wary of attributing every cognitive difficulty to age because for all we know, there may be an underlying factor present in all ages that caused the problem.

References:

Li, L., Daneman, M., Qi, J. G. & Schneider, B. A. (2004). Does the information content of an irrelevant source differentially affect spoken word recognition in younger and older adults? Journal of Experimental Psychology: Human Perception and Performance, 30 (6), 1077-1091.

Santrock, J. (2011). Life-span development, 13th edition. New York: McGraw-Hill.

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